Problem toilet flange
Don't spend the time or money on the inside flange. Purchase a 3/8 or 1/2" flange extender and connect it to the existing flange AND floor with screws. This will allow you to use standard closet bolts. Realize that you may re-set the toilet and find that the holes from the current type bolts are stripped out and need to start all over. The exit hole on the bottom of the toilet bowl is raised above the floor so if you have a 3/8" gap between the flange and tile, and another 1/2" gap to the hole, you are asking the wax seal to stretch it's limits for sealing.
If you have never made a mistake, you haven't done much.